Ranging systems and methods for decreasing transitive effects in multi-range materials measurements

ABSTRACT

A measurement system includes a gain chain configured to amplify an analog input signal; a range selector configured to select a gain between the analog input signal and a plurality of analog-to-digital converter (ADC) outputs from a plurality of ADCs, wherein each ADC output has a path, and a gain of each output path is made up of a plurality of gain stages in the gain chain; and a mixer configured to combine the plurality of ADC outputs into a single mixed output.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/016,747, to Fortney, “ADVANCED ANALOG-TO-DIGITAL CONVERSIONSYSTEMS AND METHODS,” filed Apr. 28, 2020; and U.S. Provisional PatentApplication No. 63/034,052, to Fortney, “ADVANCED DIGITAL-TO-ANALOGSIGNAL GENERATION SYSTEMS AND METHODS,” filed Jun. 3, 2020; and U.S.Provisional Patent Application No. 63/057,745, to Fortney, “SYNCHRONOUSSOURCE MEASURE SYSTEMS AND METHODS,” filed Jul. 28, 2020, each of whichis incorporated herein by reference in its entirety.

This application is related to the following applications being filedconcurrently herewith, each of which is incorporated herein by referencein its entirety: U.S. patent application Ser. No. 17/241,458, toFortney, “HYBRID DIGITAL AND ANALOG SIGNAL GENERATION SYSTEMS ANDMETHODS,” filed Apr. 27, 2021; and U.S. patent application Ser. No.17/241,472, to Fortney, “INTEGRATED MEASUREMENT SYSTEMS AND METHODS FORSYNCHRONOUS, ACCURATE MATERIALS PROPERTY MEASUREMENT,” filed Apr. 27,2021.

FIELD

This disclosure relates to measurement systems and methods. Morespecifically, it relates to avoiding glitches or errors caused bychanges in the ranging of electronics used in the measurements. Moregenerally, it relates to electronics, analytical instrumentation,software, and infrastructure for signal sourcing and signal measuring.The disclosure also relates to systems that measure signals formaterials and device characterization and other applications underchallenging experimental conditions that can cause high levels of noiseand interference.

BACKGROUND

Materials and device property measurements (e.g., electron transportproperties such as Hall, mobility and carrier concentration, etc.) oftenrequire continuous measuring over decades or orders of magnitude changesin the property. Capturing this requires switching from one set ofanalytical electronics to another, the different electronics beingconfigured for the different ranges (e.g., decades or orders ofmagnitude) in the measured property. This switching causes glitchesand/or gaps in the measured signal. It also disturbs the data collectionprocess in other ways, such as by causing transients that mightcompromise the measurement.

Analog-to-digital converters (ADCs) play a key role in the electronicsdoing the amplifying, filtering, sampling, and digitizing of measuredsignals in these measurement systems. Therefore, ADC signal processingmust be carefully configured for operational conditions, including therange of the measured property. Yet carefully configuring an ADC systemfor one range likely renders it unsuitable for others. This can lead toerror, particularly when properties vary across ranges. Selectiveamplification can address these errors. Amplifiers, however, introducetheir own errors. Those errors derive from amplifier noise, offsets,gain errors, and phase mismatches. In addition, carefully configuringgain over several ranges requires flexibility most amplification systemslack. Small signals need large gain to increase the resolution and noiseperformance. When the signals become larger over the course of themeasurement, that same large gain can cause ADCs to saturate. This cancause distortion and signal loss.

To increase flexibility in configuring gain, amplifier stages can beswitched on and off, or in and out of the signal chain. At any giventime, the amplifiers switched on are those configured for the currentsignal range. When the signal enters another range, the system switchesto another amplifier chain configured for the new range. However,glitching and discontinuity in the measurement often manifest during thetransition.

FIG. 1 shows that effect in a conventionally ranged measurement.Specifically, FIG. 1 shows conventional ranging data 104 over adiscontinuity D that results when the measured signal increases througha transition t_(TR) from lower range r1 to higher range r2. FIG. 2 showsan example of a conventional ranging setup 120 that can cause thediscontinuity D shown in FIG. 1 . Conventional ranging setup 120includes two gain chains A and B. Gain chain A is dedicated to, andconfigured for, lower range r1 (FIG. 1 ). Specifically, both the gain ofamplifier G_(A) and the ADC A are configured for lower range r1. Gainchain B is dedicated to, and configured for, higher range r2 (FIG. 2 ).This means that the gain of amplifier G_(B) and ADC B are configured forr2.

When the measured signal is small (i.e., in lower range r1), the channelselection component 122 of ranging setup 120 selects gain chain A. Asthe measured signal increases toward higher range r2, and transitionsbetween ranges at t_(TR), channel selection component 122 engageselectronics gain chain B. In this way, channel selection component 122attempts to ensure that the measurement system has configured gain overthe two different ranges. As shown schematically in FIG. 1 , however,the transition t_(TR) can introduce the discontinuity D in the measureddata. This is because switching between gain chains A and B mayintroduce transient signals, noise, or glitches resulting from “warmingup” or initiating use of the equipment dedicated to measuring over thetransitioned-to range.

Discontinuity D results in two types of ranging error. These errorsoccur when two ranges (e.g., r1 and r2) have different configuredamplifier profiles (A and B, respectively). In the first type of error,the amplifier profile mismatch causes unwanted amplitude discontinuitiesor jogs (ΔV) in measured output voltage. In the second type, temporaldata discontinuity, data flow can be cut off during a range to rangetransition. In FIG. 1 , this manifests in the data gap in the timeperiod from t_(TR) to t_(B). Temporal data discontinuity happens whenchanging ranges involves “warming up” or engaging new electronics,specifically the amplifiers associated with profile B. Collecting datais inaccurate or impossible until these transients dissipate. Transientsfrom the cooling down or shutting off of amplifiers associated withamplifier profile A may also cause delays or glitches in the measurementsystem.

Configuring setups like 120 to eliminate discontinuity D is difficult orimpossible. The configuration is limited by the simplicity and lack ofvariability of the components (G_(A), ADC A, G_(B), and ADC B).Therefore, there is a critical need for new and improved solutions forproviding robust, high quality, low noise source or measurement signalseven as measured signals vary over decades or orders of magnitude. Thereis a critical need for flexible solutions to provide smoothertransitions between ranges that diminish or eliminate suchdiscontinuities as shown in FIG. 1 .

SUMMARY

Aspects of the instant disclosure include a measurement systemcomprising a gain chain configured to amplify an analog input signal, arange selector configured to select a gain between the analog inputsignal and a plurality of analog-to-digital converter (ADC) outputs froma plurality of ADCs, wherein each ADC output has a path, and a gain ofeach output path may be made up of a plurality of gain stages in thegain chain, and a mixer configured to combine the plurality of ADCoutputs into a single mixed output.

The plurality of ADCs may comprise a first ADC and a second ADC. Thecombining the plurality of ADC outputs may be performed in accordanceto: mixed output=αE_(first)+(1−α)E_(second), where: E_(first) may be theoutput of the first ADC, E_(second) may be the output of the second ADC,and α may be a mixing parameter that varies from one to zero. The systemmay comprise two or more ADCs. A first portion of the gain chain may beconnected to a first one of the plurality of ADCs and a second portionof the gain chain may be connected to a second one of the plurality ofADCs. The range selector may select a gain for the first one of theplurality of ADCs from the first portion of the gain chain and mayselect a gain for the second one of the plurality of ADCs from thesecond portion of the gain chain. Each of the gain stages in the gainchain may be connected to each of the plurality of ADCs via one or moreswitch banks. The range selector may select a first portion of theshared gain stages for a first one of the plurality of ADCs and a secondportion of the shared gain stages for a second one of the plurality ofADCs by setting switches in the one or more switch banks. The rangeselector may comprise a first and second multiplexer. The firstmultiplexer may select the first portion of the shared gain stages. Thesecond multiplexer may select the second portion of the shared gainstages.

Selection of the first portion of the shared gain stages may compriseconfiguring a gain for the first one of the plurality of ADCs andselection of the second portion of the shared gain stages may compriseconfiguring a gain for the second one of the plurality of ADCs. Theconfiguring a gain for the first and second one of the plurality of ADCsmay comprise configuring the gains according to at least one range ofthe input signal. The mixer may be configured to, when the input signalmay be in a first range, select an output from a first ADC as the singlemixed output. The mixer may be configured to, when the input signal maybe in a second range, select an output from a second ADC as the singlemixed output. The mixer may be configured to, when the input signal maybe in between the first and second ranges, select a mix of the outputsfrom the first and second ADCs as the single mixed output.

The system may maintain the second ADC online during a first transitionperiod when the input signal may be in the first range. The system maymaintain the first ADC online during a second period when the inputsignal may be in the second range. The range selector may be configuredto configure a gain for at least one of the first ADC and second ADCbased on an anticipated range of the input signal. During a hysteresisperiod, the system may maintain the first ADC offline. The system maymaintain the second ADC online. The system may maintain a gain of thesecond ADC constant. The hysteresis period may be between the firsttransition period and the second transition period.

The plurality of ADC output paths may comprise two ADC output paths thatcan independently be configured into a high range and a low range path.The low range path may have a first gain for converting the analog inputsignal. The high range path may have a second gain for converting theanalog input signal. The second gain may be lower than the first gain.The paths may comprise a mixing device configured to combine an outputof the lower range with an output of the higher range. The system maycomprise a device configured to vary an amount of gain combined from thelow range path and the high range path. The high range path may beconnected to a first gain chain and the low range path may be connectedto a second gain chain. The system may comprise a selector to selectgain stages of the first gain chain for the first gain and to selectgain stages of the second gain chain for the second gain. Each of thefirst and second gains may comprise gain stages in a gain chain commonto the low range path and the high range path. A gain of each outputpath may be substantially the same. The mixer may average the outputsfrom each path to reduce noise in the single output.

Aspects of the present disclosure may further comprise a methodcomprising amplifying an analog input signal using a gain chain,selecting a gain between the analog input signal and a plurality ofanalog-to-digital converter (ADC) outputs from a plurality of ADCs,wherein each ADC output has a path, and a gain of each output path maybe made up of gain stages in the gain chain, and combining the pluralityof ADC outputs into a single mixed output.

A first portion of the gain chain may be connected to a first one of theplurality of ADCs and a second portion of the gain chain may beconnected to a second one of the plurality of ADCs. Each of the gainstages in the gain chain may be connected to each of the plurality ofADCs via one or more switch banks. The method may further compriseconfiguring two ADC output paths independently into a high range and alow range path. The method may comprise applying a first gain from thelow range path to convert the analog input signal. The method maycomprise applying a second gain from the high range path to convert theanalog input signal, the second gain being lower than the first gain.The method may comprise combining an output of the lower range with anoutput of the higher range. The method may comprise varying an amount ofgain combined from the high range path and the low range path.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the effect of a range transition on data collected by atypical measurement system without seamless ranging capabilities.

FIG. 2 shows an example of a conventional ranging setup 120 that cancause the discontinuity D shown in FIG. 1 .

FIG. 3 compares a voltage measurement with seamless (continuous) ranging302 with the same measurement made by a conventional setup 104 (fromFIG. 1 ) lacking seamless ranging capabilities.

FIG. 4 is one variation 400 of implementing seamless ranging via dualamplification chains.

FIG. 5 shows another exemplary amplification chain 500 according toaspects of the present disclosure.

FIG. 6A provides a schematic example of an auto-ranging algorithm 600according to aspects of the present disclosure.

FIG. 6B shows the measurement data corresponding to auto-rangingalgorithm 600.

FIG. 6C shows algorithm 600 in the form of a flowchart.

FIG. 6D shows another auto-ranging algorithm 620 in the form of aflowchart.

FIG. 7A shows another variation 700 that shares gain stages while usingmultiple ADCs (i.e., ADC A 708 a and ADC B 708 b) according to aspectsof the present disclosure.

FIG. 7B shows that the measured signal 750 a of variation 700 exhibits adiscontinuity in magnitude 752 at r1/r2 transition at t_(TR).

FIG. 8 shows another variation 800 that places a pre-amplifier (pre-amp)804 a prior to gain chain 700 c and/or a pre-amp 804 b in one of the twopaths according to aspects of the present disclosure.

FIG. 9 shows an interpolation algorithm 910 directed at eliminating ordiminishing discontinuity 752 according to aspects of the presentdisclosure.

FIG. 10A shows a generalized variation 1000 of gain selection that maybe used in accordance with the present disclosure.

FIG. 10B shows an exemplary gain path (Gain Path A) that may be createdusing variation 1000.

FIG. 10C shows another gain path (Gain Path B) of variation 1000 thatincludes two variations, a high range and a low range variation.

FIG. 11 shows another variation 1100 that includes variable gainselection by via gain stage selectors 1116 a-1116 n according to aspectsof the present disclosure.

FIG. 12A is a schematic of an exemplary mixing and auto-rangingalgorithm 1200 that may be performed by range mixers 410, 510, 710,1010, and 1110.

FIG. 12B shows a non-symmetrical auto-ranging algorithm 1250 that may beperformed by range mixers 410, 510, 710, 1010, and 1110.

FIG. 13A shows a flowchart 1300 representing a range change anticipationalgorithm 1300 that may be performed by range mixers 410, 510, 710,1010, and 1110 in implementing algorithms disclosed herein (e.g., 600,620, 910, 1200, and 1250) disclosed herein.

FIG. 13B show another part of flowchart 1300.

FIG. 13C show another part of flowchart 1300.

FIG. 14 shows an exemplary implementation of range mixing algorithm1400.

FIG. 15 illustrates a measurement signal chain 1500 between an exemplaryhead unit 1550 and exemplary measurement pod 1560 that may usevariations 400, 500, 700, 800, 1000, 1100 and algorithms 600, 620, 910,1200, 1250, 1300, and 1400.

FIG. 16 shows another exemplary variation 1600, where a head unit 1550can have six channels that can support three measure type pods 1560 aand three source type pods 1560 b according to aspects of the presentdisclosure.

DETAILED DESCRIPTION

The present disclosure introduces systems and methods that canaccommodate measurements over a wide dynamic range with relativelylittle error, noise, or glitching. Here “glitching” refers to unintendedirregularities or inconsistencies that can negatively impact ameasurement or operation. Variations disclosed herein accomplish this ina number of different ways. One way is to separately and dynamicallyconfigure gain chains for separate ranges. Another is to stich separateranges together by mixing gain profiles for the ranges. Still another isto introduce shared gain stages that can be assigned to the separateranges dynamically. These and more ways are generally referred to hereinas “seamless ranging.” They are discussed in more detail below.

FIG. 3 compares a voltage measurement with seamless ranging 302according to the present disclosure with the same measurement made by aconventional setup 104 lacking seamless ranging capabilities. FIG. 3shows discontinuity D in measured data 104 over the range transition Δt.This is because a different set of devices with different measurementprofiles (e.g., accuracy, gain, etc.) are used to measure data in rangesr1 and r2. As discussed, switching between ranges r1 and r2 in system120 may involve transient signals, noise, or glitches resulting from“warming up” or initiating use of the equipment dedicated to measuringover the transitioned-to range (r2).

FIG. 3 also shows how the transition Δt can be smoothed (continuousranging measured data 302) by the seamless ranging capabilitiesdescribed herein. This smoothing effect is represented in FIG. 3 asavoidance of discontinuity D by continuous ranging data 302. While onlytwo exemplary ranges, r1 and r2, are discussed in the context of FIG. 3, it is to be understood that the continuous ranging technique may applyto any suitable number of ranges relevant to a particular measurement.For example, the number of ranges may be three, four, or more, in somecases. In each of these cases, continuous ranging can be configured toensure a smooth transition between each range change regardless of thedirection of the range change (i.e., regardless of whether the rangechange involves an increase, as shown in FIG. 3 , or decrease in themeasured value (not shown)).

Continuous ranging addresses the two ranges r1 and r2 using separatesignal amplification/gain chains that may be applied independentlyand/or concurrently. By way of example, specific implementations will bediscussed below in the context of FIGS. 4 and 5 . Addressing each ranger1 and r2 separately and/or concurrently allows for configuration of theamplification chain for the non-active or “cold” range (i.e., the rangenot presently employed in the measurement, e.g., range r2 when t<t_(TR)or range r1 when t>t_(TR)) based on the data being gathered by theactive amplification change. Keeping the amplification chain for thenon-active or cold range online concurrently with the active rangemeasurement can avoid startup transients when the non-active range isfinally engaged. It also allows for “range mixing,” where the gainchains for each range are applied in combination in order to facilitatea smooth change in data over a transition Δt from range r1 to r2 (andvice versa). That is, amplification chains from both ranges can beapplied simultaneously to smooth the data over range transition Δt. Thiscan be done, for example, via software mixer and/or can then smoothlytransition from r1 to r2 and vice versa.

FIG. 4 is one variation 400 of implementing seamless ranging via dualamplification chains. As shown in FIG. 4 , lower gain chain 402 (i.e.,the gain chain having lower amplification) and higher gain chain 404(i.e., the gain chain having higher amplification) are identical apartfrom 1) different ADCs (408 a and 408 b, respectively) and 2) anadditional amplifier 406 in the higher gain chain 404, giving it ahigher gain than lower gain chain 402. Outputs from ADCs 408 a and 408 bare combined by mixer 410 and used in the measurement pod's 104acquisition routine for ranging measurements. In chain 400, thecombination can be weighted by a factor α. Factor α can be chosendynamically in order to ensure a smooth transition over rangingtransition Δt (e.g., using range mixing to avoid discontinuity D in FIG.3 ). While the factor α can be set by the user, it is often set by aranging algorithm (e.g., algorithms 600, 650, 910, 1200, 1250, 1300, and1400, discussed in more detail below).

FIG. 5 shows another exemplary amplification chain 500 used in seamlessranging. Chain 500 includes lower gain portion 502 and higher gainportion 504, which are identical apart from: 1) different ADCs (508 aand 508 b, respectively); 2) an additional amplifier 506 in the highergain portion 504 giving it a higher gain that lower gain portion 502;and 3) and lower gain portion 502 and higher gain portion 504 areconnected to gain stages 512 via muxes 514 a and 514 b, respectively.

As shown in FIG. 5 , the amplification supplied to lower and higher gainportions 502 and 504 from gain stages 512 a and 512 b can be selectedvia muxes 514 a and 514 b, respectively. In this way, chain 500 may usefewer dedicated amplifiers to provide the combination to mixer 510 thanchain 400. Using the same gain stages 512 a and 512 b (and amplifiers)for lower and higher gain portions 502 and 504 is not just moreefficient. It also introduces less noise in the system that can arisedue to glitches or incompatibilities between different amplifiers. Forexample, each amplifier may have transients that are avoided when theyare in constant use regardless of which range is being applied. Anyidiosyncrasies, ranging issues, or errors caused by amplifiers 512 a and512 b will be present in all ranges in which they are applied. Asdiscussed in more detail below, this can assure consistency andsmoothness in overall trends and behavior of measured data, aspects thatare often more important in materials measurements than preciselymeasured amplitudes.

As in the case of chain 400, the combination in chain 500, mixing 510can be weighted by a factor α. Factor α can be chosen dynamically inorder to ensure a smooth transition over ranging transition Δt (e.g.,using range mixing to avoid discontinuity D in FIG. 3 ). While thefactor α can be set by the user, it is often set by a ranging algorithm(e.g., algorithm 600 shown in FIG. 6A). α can be set by any methoddescribed herein relating to gain, chain, or signal mixing.

In variations including chains 400 and 500, as well as others, seamlessranging may include auto-ranging. FIG. 6A provides an illustration of anauto-ranging algorithm 600 that may be used in conjunction with seamlessranging, e.g., in variations 400 and 500. FIG. 6C shows algorithm 600 inthe form of a flowchart.

The algorithm 600 changes range as the measured signal 650 shown in FIG.6B changes increases from range r1, r2, and r3. Signal 650 transitionsfrom range r1 to r2 at t=t_(TR(1-2)) and from range r2 to r3 att_(TR(2-3)). FIG. 6A shows the response of the algorithm 600, in termsof applying gain chains dedicated to ranges r1, r2, and r3, over thosetransitions.

As shown in FIGS. 6A and 6C, the algorithm 600 provides a gainconfigured for 100% r1 (e.g., drawing from higher gain portion 404 inchain 400 of FIG. 4 to provide higher gain to the lower of the tworanges) during the period 602, prior to the transition from r1 to r2(t_(TR(1-2))). FIGS. 6A and 6C also show that algorithm 600 mixes thegain profiles for r1 and r2 as the measured signal approaches thetransition t_(TR(1-2)) (e.g., drawing from higher gain portion 404 andlower gain portion 404). This pre-transition, r1/r2 mixing period islabeled 604. As discussed above, mixing avoids glitches and/or gaps inthe data during the r1/r2 range transition. After the r1/r2 transitionat t_(TR(1-2)), the algorithm 600 applies r2 gain without mixing (e.g.,drawing from lower gain portion 402 in chain 400 of FIG. 4 ). FIGS. 6A,6B, and 6C show that the algorithm changes from r2 to r3 at t_(TR(2-3))in the same way, i.e., first by mixing gain profiles for r2 and r3during period 608, then by providing r3 configured gain only duringperiod 610.

FIG. 6A also shows a region of hysteresis 612 during period 606 (r2only). During hysteresis 612, there is no anticipated ranging (i.e.,only one gain portion of the gain chain is active, in this case the gainchain for r2). The applied gain during hysteresis may also be constant.This avoids switching back and forth between ranges due to noise orsignal variation. Once the measured signal 650 edges closer to r3, thehysteresis period 612 ends. Period 614 represents a period in which arange change from r2 to r3 is anticipated by engaging the gain chain(not shown) for r3. The gain chain corresponding to r3 is engaged during614 both for the purposes of calibration and to avoid transients, asdiscussed above. Although no hysteresis or anticipation of range upportions are shown for the r1/r2 transition, it is to be understood thatthey may be applied to that transition as well.

Though FIG. 6A shows operation of algorithm 600 as the measured signalincreases, it is to be understood that the algorithm applies the sameway with the measurement signal decreases (e.g., from higher range r3 tolower range r2, then to lowest range r1). This is shown via flowchart620 in FIG. 6D. In this case, the algorithm 600 would have anticipaterange down periods rather than anticipate range up periods (e.g.,transitioning downward from r3 to r2 at t_(TR(3-2)) (step 624 in chart620), etc.).

Although FIGS. 6A, 6B, and 6C show algorithms 600 and 620 handling rangechanges among three exemplary ranges r1, r2, and r3, it is to beunderstood that it may handle range changes among any number of rangessuitable for the experiment in the same manner. Other variations ofalgorithms 600 and 620 can include many other algorithms and/orrange/parameter settings and any suitable number of range transitions.

Mixers 410 and 510 in chains 400 and 500, respectively, can operateaccording to any suitable mixing algorithm to achieve the smoothingeffect shown in FIG. 3 (302). Mixers 401 and 501 may be digital. Theymay have no need for independent calibration. In one variation, themixed output of 410 and 510 may be controlled by algorithms similar tothe following:output signal V (for Mixer 402 or 502)=αE _(A)+(1−α)E _(B)  (1)

where

-   -   E_(A) is the output of the first ADC (ADC A 408 a or ADC A 508        a),    -   E_(B) is the output of the second ADC (ADC A 408 b or ADC A 508        b), and    -   α is a mixing parameter that can vary, for example, from one to        zero.

It is to be appreciated that equation 1 is not the only mixing algorithmthat can be applied by mixers 410 and 510. For example, mixers maysimply average the outputs of each path to reduce noise. Equation 1applies a linear weighting (α) to the contributions of E_(A) and E_(B).However, non-linear weightings are contemplated and should be consideredwithin the scope of the present disclosure. In fact, the weighting mayinclude any suitable mathematical form. Examples include, but are notlimited to quadratic, cubic, and any suitable polynomial. Exponentialand logarithmic functions, as well as differential equations, are allcontemplated within the scope of this disclosure.

The exact form of the weighting or mixing function should depend onfactors such as the gains of the various amplifiers in the system (e.g.,amplifiers in 402, 404, and 512 and amplifier 506), as well as the othercomponents, such as the ADCs (e.g., ADCs 408 a, 408 b, 508 a, and 508b). It may also depend on the particulars of the mixers 401 and 510 usedin the circuits. It may depend on the following exemplarycharacteristics of these components, e.g., frequency response, gainvalue, non-linearity, sensitivity to variations in input. In addition,parameter α, need not vary from one to zero, as in the example above.Parameter α, as well as any other value employed by mixers 410 and 510,can depend on the specifics of the gain stages in chains 402, 404, and512 as well as gain 506. It may include any suitable value for balancingthe gain and eliminating or diminishing discontinuity D (FIG. 3 ).

FIG. 7A shows another variation 700 that shares gain stages while usingmultiple ADCs (i.e., ADC A 708 a and ADC B 708 b). FIG. 7A shows thearchitecture of the chain 700 itself. FIG. 7B is plot 750 comparing theresponse 750 a of chain 700 with a prior art, conventional rangingsystem such as 120.

Chain 700 includes two signal paths 700 a and 700 b inclusive of an ADC(ADC A 708 a and ADC B 708 b, respectively) and a multiplexer (mux, 706a and 706 b, respectively). Multiplexers 706 a and 706 b select fromgain stages 704 a-704 c from gain chain 700 c. Therefore, signal paths700 a and 700 b have independently configurable gains based on thoseselections.

Each independently configurable gain delivered to paths 700 a and 700 bcan be any combination of the output of amplifiers 704 a, 704 b, and 704c having gains A1, A2, and A3, respectively. Each of gains A1, A2, andA3 may be 1, any suitable positive value greater than 1, and anysuitable negative value with an absolute value greater than 1. Althoughthe gains can be selected for any reason and based on any criterion,they are typically selected by muxes 706 a and 706 b based on the rangeof input signal 702 in order to best accommodate that signal. It isunderstood that many different combinations are possible and within thescope of the instant disclosure.

For example, the input signal 702 may be in a range that is bestamplified by the combined gain from gain stages 704 a and 704 b (i.e., again equal to the product of A1 and A2) and ADC A 708 a. This range may,for example, correspond to lower range r1 in FIG. 6A requiring arelatively high gain. In this case, mux 706 a would select input 707 a,to send that gain to ADC A 708 a. After processing in ADC A 708 a, thesignal is sent to mixer 710. In this case, since the ADC A 708 a is theappropriate range and signal, the mixer 710 would select only the ADC A708 a input (e.g., set α in equation 1 equal to 1). At the same time,mux 706 b may be set such that ADC 708 b has an configured gain forupper range r2. This may be a lower gain than for lower range r1corresponding to a higher signal amplification. Merely by way ofexample, this lower gain may be A1. In this example, ADC B 708 b is notused to generate output signal 712 as long as the input 702 is in ranger1. Typically, one would say that the path 700 b and its associatedunused range are cold because they are not actively providing output tomixer 710. Even while cold, however, the path 700 b may still beoperational in order to avoid transients that occur during turn on orwarm up.

If the input signal 702 increases such that it risks saturating ADC A708 a by closing in on transition t_(TR), ADC B 708 b (the “cold” range)may be engaged. The path associated with ADC B 708 b can set to a higherrange (lower gain). For example, ADC B 708 b is fed the output of gainstage A1 (704 a), which will result in ADC B 708 b being in a higherrange (lower gain) than ADC A 708 a in path 700 a.

While input signal 702 is at a desired level for ADC A708 a, mixer 710is set so that only output 712 receives only ADC A 708 a's contribution.This corresponds to lower range r1 in FIG. 3 , far from transition pointt_(TR). However, as input signal 702 increases toward t_(TR) (and upperrange r2, for which ADC B708 b is configured), it becomes moreadvantageous for ADC B 708 b to take over processing. Before thetransition t_(TR), ADCs 708 b “warms up” by starting to measure inputsignal 702. In this configuration, which corresponds to step 614 inFIGS. 6A and 6C, mixer 710 is still set such that only the signal fromADC A 708 a is sent to output 712. Once transients in the ADC B 708 bprocessing of the input signal 702 die off, mixer 710 starts to provideto output 712 a signal that is a combination of outputs from ADC A 708and ADC B 708 b. This mixed output can be, for example, according toequation 1. Mixer 710 gradually increases the contribution from ADC B708 b, until the system is well in range r2. At that point,corresponding to step 606 in FIGS. 6A and 6C, mixer 710 may shut off oreliminate the contribution from ADC A 708 a. This is because ADC B 708 bis configured for r2. In the example case, mux 706 b is set such thatADC B 708 b receives lower gain (A1 only, as opposed to the product ofA1 and A2). This corresponds to input 707 b. The generation of output712 by mixing signals from the two ADC paths 700 a and 700 b to smooththe transition over D (FIG. 6A) is seamless ranging.

In this scenario, idiosyncrasies and/or errors associated with gainstage 704 a (gain of A1) are common between to the measured signal 750 a(FIG. 7B) of both ranges r1 and r2 and their range paths 700 a and 700b, respectively. Therefore, the range to range transition t_(TR) hasgain commonality. This reduces the discrepancy between ranges. Theeffect on measured data is shown schematically in FIG. 7B. Specifically,FIG. 7B shows how a signal 750 a measured by 700 is more similar inranges r1 and r2 (portions A and B, respectively) than the same outputmeasured by a prior art configuration (e.g., 100 shown in FIG. 1 ). Inother words, measured signal 750 a is more similar when they aremeasuring the same signal (seamless ranging) as compared to thecompletely different sets of gains in each range (prior art). In FIG.7B, both the prior art system and seamless ranging system 750 a have thesame output for portion A (range r1).

Once the input signal 702 b passes to ADC B 708 b, ADC A 708 a is nowcold. Even while cold, the gain of ADC A is 708 a remains configured toanticipate where the signal will go next. ADC A 708 a could, forexample, stay in r2 configured range to anticipate a return to thatrange. Alternatively, ADC A 708 a may change its range by resetting mux706 b for another gain. ADC A 708 a may do this in anticipation of thesignal continuing to increase or decrease, depending on the initialconditions of each signal path.

As discussed in the context of FIG. 6D, the above-described transitioncould be run in reverse for a decreasing input signal 702. In otherwords, if signal 702 is decreasing from range r2 to r1, mixer wouldfirst be set to feed to output 712 only the contribution from path 700b. This is because ADC B 708 b is configured for range r2 by setting mux708 a to receive input 707 b (lower gain A1). As input 702 decreasestoward t_(TR), ADC 708 a is warmed up and turned on so that transientsdie off. In this phase, mixer 712 is still set such that output 712receives only the 708 b contribution. Once input 702 is close to t_(TR),mixer 710 is set to combine 700 a and 700 b contributions to create aseamless transition. As input 702 decreases beyond t_(TR) to r1, mixer710 is reset so that only the configured path for r1 (i.e., 700 aincluding ADC A 708 a) contributes to output 712. As discussed in theabove example, this gain may be the product of A1 and A2 set by mux 706a.

In a system with many gain stages like 700, the input signal 702 can bepassed back and forth between the ADCs 708 a and 708 b as the inputsignal increases or decreases. Each time the cold ADC would anticipatethe range needed for the changing signal, as described above. Duringthis process, gain can be changed for the cold ADC while the output isbeing taken from the active ADC. This results in a constant output inthe desired range, and results in reduced discrepancies due to gainvariations in each range, as shown in FIG. 7B.

FIG. 7B shows that the measured signal 750 a exhibits a discontinuity inmagnitude 752 at r1/r2 transition at t_(TR). This is merely for thepurposes of illustration and may not be present in all implementations.Discontinuity 752 arises from the situation in which the gains appliedto paths 700 a and 700 b, configured for each range r1/r2, are slightlyincompatible at transition t_(TR). In many variations, it may bepossible to tune the gains for each path 700 a and 700 b to eliminatediscontinuity 752. However, it may be more important to configure thegains to best represent their respective ranges. In this case,discontinuity 752 would be a known artifact of the measurementelectronics and can be dealt with in a number of ways in post processingof the measured data 750 a (e.g., by curve fitting/smoothing, etc.).

FIG. 8 shows another variation 800 that places a pre-amplifier (pre-amp)804 a prior to gain chain 700 c and/or a pre-amp 804 b in one of the twopaths. FIG. 8 shows pre-amp 804 b in path 700 b associated with ADC B708 b. However, it is to be understood that pre-amp 804 b could also beplaced in a similar position in path 700 a associated with ADC A 708 a.Aside from the addition of pre-amps 804 a and 804 b, variation 800 isidentical to variation 700 of FIG. 7A.

Pre-amps 804 a and 804 b can provide several benefits to variation 800.For example, pre-amp 804 a can buffer input signal 702 from othercomponents in variation 800. This can be advantageous because connectingthe input 702 directly to multiple buffers or switching elementsdegrades performance. These elements often impart bias currents andswitching capacitance to the input 702. Pre-amp 804 b can be placed inthe path (either 700 a or 700 b) associated with a range that typicallyrequires an extra gain. This can be, for example, the lowest range(e.g., range r1 in FIG. 6A). Having an extra gain stage “hard wired”into one of the paths makes applying the appropriate gain to that pathsimpler and easier.

FIG. 9 shows an interpolation algorithm 910 directed at eliminating ordiminishing discontinuity 752. Algorithm 910 may be performed by mixer710 (FIGS. 7 and 8 ) for both paths 700 a and 700 b.

In some applications, particularly in material research, thediscontinuity 752 itself may be bigger problem than other sources ofquantitative error. This is especially true with the overall characterof the measured signal 750 a, rather than its precisely measured value,is most important for describing materials properties. In many instancesthe measured value may be assessed in relative or normalized terms, toemphasize the behavior over the precise amplitude. In these cases, mixer710 can interpolate its two inputs from ADCs 708 a and 708 b in order tomaintain a smooth transition between ranges r1 and r2. Such aninterpolation can be performed via equation 1. It can also be performedusing another suitable mathematical or signal processing means forinterpolating the signals from ADCs 708 a and 708 b. As shown in FIG. 9, the interpolation 910 is typically performed only over a time period920 close to the transition time t_(TR). Time period 920 may correspond,for example, to Δt shown in FIG. 3 . However, it is to be understoodthat the interpolation 910 need not be limited to any particular timeperiod. Since the contribution of each of the signals from the two ADCs708 a and 708 b is variable, the interpolation 910 may be executingthroughout measurement.

FIG. 10A shows a variation 1000 that includes additional latitude forgain with selection for each path 1000 a and 1000 b associated withmultiple amplifiers 1004 a-1004 n in common gain chain 1000 c. Gainstage selection can be made in variation 1000 by two series of switchbanks 1006 a and 1006 b. Each bank includes switches, e.g., switch 1014a that can connect or disconnect a data converter (e.g., ADC) 1008 a or1008 b to each gain stage in the chain 1000 c. The way each amplifier1004 a-1004 n can be independently connected.

It is to be understood that the switch banks 1006 a and 1006 b can beimplemented in a number of suitable ways. Solid state switching can beused. Alternatively, mechanical relay switching can be used. Any othersuitable switching or connection method can be used. The individualswitches (e.g., 1014 a) may be present and operated individually.Alternatively, they may be operated as part of an integrated circuit orother integrated device. They may be triggered by any suitable means,including by user input, any of the algorithms described herein (e.g.,algorithms 600, 620, and 910, etc.) Moreover, the switch banks 1006 aand 1006 b may be operated dynamically such that the switching and thegains fed to data converters 1008 a and 1008 b can be changeddynamically (e.g., at any point in ranges r1 and r2 in FIG. 6A).

FIG. 10A illustrates how gain paths can be made that use the common gainchain to amplify an input signal. The points in the common gain chain1000 c, before or after each gain stage 1014 a-1014 n, can be selectedby multiple ranges. In FIG. 10A, a switching means 1006 a and 1006 band/or controller can be used to select the point on the common gainchain 1000 c and pass the input signal to either the top data converter1008 a or the bottom data converter 1008 b.

As shown in FIG. 10A, mixer 1010 selects or mixes the output from dataconverters 1008 a and 1008 b to feed to data output 1012. Mixer 1010 canoperate in a similar or the same way as mixers 410, 510, and 710. Forexample, mixer 1010 may use equation 1 to mix 1008 a and 1008 b outputs.It may do so based on any information used by mixers 410, 510, and 710(e.g., user input, algorithm 600, etc.).

Although FIG. 10A shows only two converters, it is to be understood thatvariation 1000 (as well as variations 500, 700, and 800) can be usedwith any suitable number of data converters. One exemplary configurationis to assign a data converter for each independent range. Therefore, ifthe measurement includes four ranges, r1-r4, for example, fourindependent data converters may be used.

FIG. 10A shows the variation 1000 includes any number (n) of gain stages1004-1004 n in gain chain 1000 c. Generally, the more gain stagesincluded in 1000 c, the more flexibility to allow data converters 1008 aand 1008 b to represent a particular range. In several variations, suchas variation 1000, n outnumbers the number of data converters 1008 m bya factor of two or more.

Although FIG. 10A shows gain stages 1004 a-1004 n appearing to be thesame or similar type, this is not necessarily the case. In variations,it may be advantageous to use different types of gain stages withdifferent gains. A benefit from having a common gain chain 1000 c isfewer parts of the system need to be calibrated. In conventionalsystems, two completely independent gain paths needed to be calibrated.In this disclosure, the gain stages can be calibrated independent fromthe ranges. This can decrease the time it takes to calibrate the overallsystem.

Typically, most or all the gain stages in chain 1000 c are active. Insome cases, it may be useful to deactivate certain gain stages 1004a-1004 n while not in use (e.g., to generate active or anticipatedranges). For example, some types of gain stages 1004 a-1004 n may nothandle saturation well without producing errors. In that case, such gainstages would advantageously deactivate once a risk of saturation wasdetected. Doing so may allow for faster transitions (i.e., by activatinga range only when that range is able to properly amplify the signal).Unused ranges 1004 a-1004 n could also be deactivated to reduce powerdraw, heat generation, etc.

FIG. 10B shows an exemplary gain path (Gain Path A) that may be createdusing variation 1000. To create Gain Path A, switch 1014 c is engaged.This causes Gain Path A to be amplified by gain stages 1004 a and 1004 b(and no other gain stages). The amplified signal is then sent to dataconverter 1008 a. The path is then mixed with another path by mixer 1010and sent to data output 1012. In variations, mixer 1010 may send onlythe signal from Gain Path A to data output 1012. In others, it may mixpaths by any of the means or algorithms disclosed herein (e.g.,equation, algorithm 600, etc.).

FIG. 10C shows another gain path (Gain Path B) that includes twovariations, a high range and a low range variation. Both high and lowvariations use data converter 1008 b instead of converter 1008 a.Therefore, Gain Path B can be separately and independently engaged withGain Path A. Gain Paths A and B can be mixed together by mixer 1010 toform data output 1012.

The higher range path of Gain Path B includes less gain and may be moreappropriate for a higher range (e.g., r2 in FIG. 6A). It does so bytriggering switch 1014 f, which causes the path to include gain fromonly one stage, i.e., 1004 a. The lower range path is obtained bytriggering switch 1014 h while switch 1014 f is not triggered. The lowerrange path includes two extra gain stages, i.e., 1004 b and 1004 c,along with gain stage 1004 a. This gives it a much higher gain that maybe more appropriate for a lower range (e.g., r1 in FIG. 6A).

Variation 1000 may switch between any of these gain paths, as needed. Itmay do so, for example, according to any of algorithms 600, 620, and910. For example, since Gain Path A is lowest gain, variation 1000 mayuse Gain Path A initially. It may simultaneously have Gain Path B onlineto warm it up and remove transients. In this scenario, Gain Path B wouldbe in its lower range configuration in anticipation that the measuredsignal would use this first since it is increasing from a lower range(i.e., the lower range associated with Gain Path A). As the measuredsignal continues to increase, mixer 1010 may mix Gain Paths A and B,with Gain Path B being in the lower range configuration. As the measuredsignal continues to increase, the mixer 1010 may send only Gain Path Bto data output 1012. As the signal continues to increase beyond thispoint, the higher range configuration of Gain Path B may be triggered byflipping 1014 h off and 1014 f on. This would give the input signal 1002the least amount of gain (i.e., only the gain from gain stage 1004 a)corresponding with being in the highest range.

FIG. 11 shows another variation 1100 that includes variable gainselection by another means, namely gain stage selectors 1116 a-1116 n.Variation 1100 selects gain from gain from among two stages 1104 a and1104 b. However, it is to be understood that this is merely exemplary.Any suitable number n of gain stages 1104 may be included in 1100.

In variation 1000, each data converter 1108 a-1108 n is connected to itsown gain stage selector 1116 a-1116 n. However, other configurationswhere data converters 1108 share gain stage selectors 1116 are alsopossible.

Variation 1100 includes a number of data converters n that can be large.In general, the number of converters n can be chosen so that there isone converter for each range. In other situations, it may beadvantageous to include either more converters than ranges or fewer.Multiple ranges/gain stages are also useful, for example, in measuringpulse input signal applications. If the input signal transitionsmultiple ranges, then it may be useful to measure that pulse acrossseveral ranges with different gains. It is to be understood that anysuitable number of gain stages, greater or less than n, may be used.

It can be useful to have a range which always measures at a point in thecommon gain chain, while other ranges pass the signal back and forthbetween desired gains. One variation can use a low-cost ADC toinitialize the input signal with a low gain and use this information toquickly configure the gain in high quality ADCs. This may be valuablefor inputs that change between different sources. Input signals withlarge amplitude spikes can also cause problems for measurement systems.Therefore, by having a multitude of ADCs measuring simultaneously, onecan achieve accurate measurements when the input is in its “normal”range, but still be able to measure a signal spike. In other variations,input can benefit from using different types of ADCs simultaneously tomeasure the signal. High speed ADCs along with high resolution ADCswould allow for different types of signals to be measured and convertedwithout sacrificing performance. All of these variations can use theanticipation algorithm, along with other ADCs measuring the input signalfor other purposes. Many communication signals exhibit this type ofsignal characteristic.

As shown in FIG. 11 , variation 1100 includes a range mixer 1110. Rangemixer 1110 mixes the outputs of data converters 1108 a-1108 n to provideto data output 1112. Range mixer 1110 can mix the outputs according toany method disclosed herein in the context of other range mixers (e.g.,in the context of range mixer 1010). Many different types of mixingalgorithms can also be designed to combine the different ranges to moreaccurately measure a changing input signal.

As shown in FIG. 11 , each gain stage selector 1116 a-1116 n can provideany combination of gain stages 1104 a and 1104 b to data converters 1108a-1108 n. The combination can be selected by any means of gain selectiondisclosed herein, including by user input, any of the algorithmsdisclosed herein (e.g., 600, 620, and 910).

FIG. 12A is a schematic of an exemplary mixing and auto-rangingalgorithm 1200 that may be performed by range mixers 410, 510, 710,1010, and 1110. Algorithm 1200 mixes three ranges A1, A2, and A3, asshown in FIG. 12A. For purely illustrative purposes, A1>A2>A3. It shouldbe understood that higher gain is typically associated with a lowerrange in measured variable, and vice versa. Therefore, an exemplary gainconfiguration of A1>A2>A3 would most likely correspond to the followingmeasured range configuration: r1<r2<r3. In this situation, the highestgain A1 would apply to the lowest range in measured data r1, etc. FIG.12A shows the gain increasing from A3 to A1 (top to bottom) as the valueof the measured signal decreases. That is, as the measured signaldecreases in range from r3 to r1.

When the measured signal is in the highest range (e.g., range r3 in FIG.6A), algorithm 1200 applies lowest gain A3. As the measured signaldecreases and approaches the next lowest range, i.e., the range wherenext higher gain A2 is desired, the mixer (e.g., 410, 510, 710, 1010,and 1110) becomes active. This occurs at stage 1204. In stage 1204, themixer combines A3 and A2 to smooth the transition. At 1206, thetransition between A3 and A2 ranges is complete. The mixer applies A2only. At stage 1208, the measured data is solidly in the A2 range. Hereany switching between stages or mixing by the mixer is erroneous.Therefore, algorithm 1200 applies a hysteresis that prevents changes inanticipated range. This ensures that there is no erroneous switching ofelectronics based on noise or aberrations in the data. At step 1210, themeasured data decreases further to approach the lowest range in measuredvalue (e.g., r1 in FIG. 6A) where highest gain A1 is most appropriate.Therefore, algorithm 1200 “warms up” the A1 gain profile. Mixer does notactually engage A1 gain with regard to the measured signal at this time.Instead, it is switched on to get rid of any transients that may occur.The mixer starts to actively mix A2 and A1 ranges at step 1212. This isbecause the measured signal is now close enough to the highest gainA1/lowest measured range r1 to smooth the transition. Finally, at step1214, the measured data is now solidly in the A1 range. The mixerprovides only the A1 gain.

It is to be understood that, although FIG. 12A has been explained interms of increasing gain from the lowest A3 gain to the highest A1(decreasing range from highest measured range r3 to lowest measuredrange r1), FIG. 12A is bi-directional. That is, algorithm 1200 can alsoproceed where the gain decreases from A1 to A3, corresponding to anincrease in the range of measured data from r1 to r3. In that case,algorithm 1200 would follow steps in the reverse order, i.e., 1214-1202.

The auto-ranging algorithms can be different for any application and donot need to be symmetrical or linear, as shown in FIG. 12A. Anon-symmetrical variation 1250 is shown in FIG. 12B. In FIG. 12B, thereare three ranges specified by the order of magnitude of the measureddata: 10, 1, and 0.1. Note that the numbers 10, 1, and 0.1 refer toorders of magnitude of ranges in the measured variable (e.g., voltage).This is unlike FIG. 12A where the ranges are referred to by their gainsA1, A2, and A3. Since gain is inversely related to the measuredvariable, the lowest measured range 0.1 corresponds to the highest gain(A_(0.1)). The highest measured range 10 corresponds to the lowest gain(A₁₀). Because the change between the 10 and 0.1 ranges represents achange of two orders of magnitude is measured data, extra care needs tobe taken in range mixing. The measured signal is so small in the 0.1range, in particular, that it may be easily overwhelmed by range mixing.Therefore, algorithm 1250 applies range mixing with caution.

When the measured signal is in the highest measured data range 10,algorithm 1250 applies lowest gain (A₁₀) appropriate for that range.This is stage 1252 in FIG. 12B. As the measured signal decreases andapproaches the next highest measured data range, 1, the mixer becomesactive. This occurs at stage 1254. In stage 1254, the mixer combinesgain for the 10 (A₁₀) and 1 (A₁) ranges to smooth the transition. At1256, the transition between 10 and 1 ranges is complete. The mixerapplies the gain for 1 (A₁) only. However, since the difference inranges between 1 and 10 ranges is so large, the electronics for the 10(A₁₀) measured data range is kept warm. Although there is no mixing, themixer is ready to switch between ranges as needed to prevent saturation.At stage 1258, the measured data so solidly in the 1 range thatswitching to range 10 is not possible. Here any switching between stagesor mixing by the mixer is erroneous. Therefore, algorithm 1250 applies ahysteresis that prevents changes in anticipated range. This makes surethere is no erroneous switching of electronics based on noise oraberrations in the data. At step 1260, the measured data decreasessufficient to approach the lowest 0.1 measured data range. In this stepthe mixer anticipates a range change downward by engaging theelectronics for the 0.1 range, but keeping them offline (i.e., notmixing ranges). As the measured data continues to decrease toward the0.1 range, algorithm 1260 enters step 1262. In this stage, the mixeractively combines the gains for the 0.1 (A_(0.1)) and 1 (A₁) ranges tosmooth transition to the 0.1 range. Finally, at step 1264, the measureddata is now solidly in the 0.1 range. The mixer provides only the gain(A_(0.1)) associated with the lowest 0.1 measured data range.

It is to be understood that, although FIG. 12B has been explained interms of decreasing measured range (increasing gain) from the highest 10range to the lowest 0.1 measured data range, FIG. 12B is bi-directional.That is, algorithm 1250 can also proceed where the measured data isincreasing from range 0.1 to 10, and the corresponding gain isdecreasing. In that case, algorithm 1260 would follow steps in thereverse order, i.e., 1264-1252.

FIGS. 13A and 13B show a flowchart representing a range changeanticipation algorithm 1300 that may be performed by a mixer inimplementing algorithms disclosed herein (e.g., 600, 620, 910, 1200, and1250).

Algorithm 1300 begins by initializing the input signals. At step 1302,the input signal is measured. A first range A is made active forcomparison with the input signal at step 1302. That comparison is madeat step 1304.

If range A is not desired, algorithm 1300 determines whether range istoo low or high in step 1306. If the range is too high, the range isdecreased at step 1308 a. If range A is too low for the measured inputsignal, the gain for range A is increased at step 1308 b. Whether rangeA is increased or decreased, the next step 1310 waits for any transienteffects caused by the gain change to dissipate. Subsequent to transientdissipation, algorithm 1300 performs step 1302 again to measure thesignal and compare with modified gain for range A.

When step 1304 determines that the gain associated with range A isdesired for the measured signal, algorithm 1300 proceeds to step 1312.At step 1312, the algorithm anticipates a change from range A to a newrange B. It “warms up” the electronics associated with new range B. Atstep 1314, algorithm 1300 initiates inputs based on its assessment ofnew range B and the measured input. At step 1316, algorithm 1300measures the input in both ranges A and B. At step 1318, algorithm 1300selects the best range for the measured input among ranges A and B forbeing active (i.e., for use in the measuring the input).

Algorithm 1300 then begins the process of deciding a switching thresholdbased on the measured input and current ranges A and B. In step 1320,algorithm 1300 determines if the active range is less than a down rangeswitching threshold. If the active range is less than the down rangethreshold, algorithm 1300 performs step 1322 to determine if the cold orunused range among ranges A and B is in the lower range. If the coldrange A or B is in the lower range, algorithm 1300 proceeds to step 1324to initiate mixing. If the cold range A is not the lower range, thealgorithm 1300 sets the cold range to the lower range in step 1326, thenproceeds to step 1324 to initiate mixing.

If the algorithm 1300 determines that the active range is not less thana down switch threshold in step 1320, it proceeds to step 1328. At step1328, the algorithm 1300 determines whether or not the active range isgreater than an up switch threshold. If so, the algorithm 1300 proceedsto step 1330 to determine if the cold or unused range among ranges A andB is the higher range. If the cold range A or B is in the higher range,algorithm 1300 proceeds to step 1324 to initiate mixing. If the coldrange A is not the higher range, the algorithm 1300 sets the cold rangeto the higher range in step 1332, then proceeds to step 1324 to initiatemixing.

If the algorithm 1300 finds that the active range is not less than adown switch threshold (step 1320) and finds it is also not greater thanthe up switch threshold (step 1328), the algorithm proceeds to step1334. At step 1334, the algorithm 1300 applies a hysteresis to preventrange changing. This is because the measured signal is not within therange changing up or down thresholds. Therefore, any decision to changeranges would be based on erroneous noise or glitches in the data. Oncehysteresis is applied, the algorithm proceeds to step 1324 to initiatemixing.

At step 1324, the algorithm 1300 begins steps to initiate mixing. Thefirst step is to make sure the cold range is settled. If the cold rangeis settled, the system is ready for mixing. Then algorithm 1300 proceedsto step 1326 to determine whether or not to mix in ranges. If thedecision is made to mix, algorithm 1300 mixes the ranges at step 1328and then provides the mixed signal as output at step 1330. If thedecision is not to mix, the algorithm sets the output to the activerange at step 1332. If the cold range is not settled, the algorithm 1300proceeds from step 1324 to step 1332 to set the output to the activerange. After the output is set to the active range at 1332, then thesignal is output at step 1330.

Ranging does not need to be accomplished exclusively by algorithm. Itcan also be accomplished via hardware. FIG. 14 shows parameters inputone such exemplary hardware variation 1400. In 1400, there is a “main”channel capable of measuring the named range, and an “aux” channel withless gain. At each ranging update, the percentage of full-scaleindication on the main channel can be used to determine behavior asfollows:

TABLE 1 Parameters of mechanical ranging algorithm 1400. % of MainChannel Next Range Interpolator State >120% Range up if it exists Allaux 100%-120% No change All aux  70%-100% No change Active, scaled basedon % of main 10%-70% No change All main  <10% Range down if it existsAll main

FIG. 14 shows how range mixing algorithm 1400 will behave for differentinput levels. More particularly, FIG. 14 shows how algorithm 1400 willmix (i.e. “Mixing”) different channel gains A and B based on the inputs(i.e., Range, Range Enumeration, Input Voltage, Enable Preamp, EnableStage B, Enable Stage C, Channel A Gain, and Channel B Gain). The inputsare for two gain channels A and B and two sample stages B and C. “RangeEnumeration” is an integer representation of a particular range (i.e.,10 V range is “0,” 1 V range is “1,” 100 mV range is “2,” etc.).

FIG. 15 illustrates a measurement signal chain 1500 between an exemplaryhead unit 1550 and exemplary measurement pod 1560 that may usevariations 400, 500, 700, 800, 1000, 1100 and algorithms 600, 620, 910,1200, 1250, 1300, and 1400. Although FIG. 15 shows particular aspects ofseamless ranging in system 1500, it should be understood that system1500 can accommodate any variation disclosed herein. Both source pods1560 and head units 1550 of system 1500 are described in more detail inU.S. patent application Ser. No. 17/241,472, to Fortney, “INTEGRATEDMEASUREMENT SYSTEMS AND METHODS FOR SYNCHRONOUS, ACCURATE MATERIALSPROPERTY MEASUREMENT.”

As shown in FIG. 15 , the head 1550 includes measure channels 1502. Inthe exemplary case there are two input measure channels, one for a RangeA and one for a Range B, each with its associated ADC. Note that, insome variations, each measurement unit 1560 will have an associatedconfiguration 1500 in communication with head 1550. This means that avariation with three measurement pods 1560 may have six ADCs. It is tobe understood than any suitable number of measurement channels ispossible, depending on the particular measurement and the number ofranges involved, which may be substantially greater than two (e.g.,three, four, or more). The measurement channels 1502 may be obtainedfrom measurement pod 1560 via a number of variable amplifiers 1520 andanalog filters 1504, as shown in FIG. 15 . Gain on the amplifiers 1520may be set as described in the context of gains 1520 a-1520 c in FIGS.10-12 . Channels 1502 may be combined 1506 with a range mixing signal1508 and sent to for demodulation 1510 via lock-in. Demodulation may beinformed by reference signals (e.g., Reference (lock-in) and Reference+90 degrees (lock-in) 1512) and subject to Digital filters 1514 forsignal refinement.

The signal can be processed in any number of ways including DC, AC, orLock In processing. Range decisions can be made on the basis of the peakvalues of the Measured sample signal regardless of what other processingis being performed for the sake of the measurement. This is because thepeak values are what would cause amplifier overload. As shown in FIG. 15, range mixer 1508 may further provide output for Ranges and settings1516 ultimately fed back to amplifiers 1520 and analog filters 1504 toadjust gain and processing of the Measured sample signal, specificallywith respect to each of Ranges A and B. Range mixer 1508 may perform asdescribed above in the context of range mixers 410, 510, 710, 1010, and1110. This process is referred to as continuous measurement rangingand/or range mixing. Its purpose is to insure against glitches ormeasurement inconsistencies that might otherwise occur when the measurepod 1560 must change its acquisition parameters to adjust for a changein range of the Measured sample signal.

Measurement pod 1560 may further include digital (non-analog) circuitrycapable of performing various functions, including analysis,communication of data, command information, power regulation, timing,and communication with external devices. In variations, measurement pod1560 has the capability to de-activate this non-analog circuitry whileperforming a measurement or providing a source signal. Doing sodecreases the amount of interference and noise in the signal ormeasurement. For the same reason, digital signals in the measurement pod1560 may be isolated from the source pod 1560 and the head 1550.

Other variations of system 1500 include any suitable number of heads1550, source pods and measure pods 1560. For example, FIG. 16 showsanother exemplary variation 1600, where a head unit 1550 can have sixchannels that can support three measure type pods 1560 a and threesource type pods 1560 b. In this variation, the head 1550 is also shownconnected to an optional computer 1602 and three exemplary sampled ordevices under test (DUTs) 1570. Again, this configuration is merelyexemplary. There is no requirement for equal numbers of measure 1950 aand source 1950 b pods. One source 1950 a could provide the excitationsignal for all three DUTs 1570, for example.

While various inventive aspects, concepts and features of the inventionsmay be described and illustrated herein as embodied in combination inthe exemplary embodiments, these various aspects, concepts and featuresmay be used in many alternative embodiments, either individually or invarious combinations and sub-combinations thereof. Unless expresslyexcluded herein all such combinations and sub-combinations are intendedto be within the scope of the present inventions. Still further, whilevarious alternative embodiments as to the various aspects, concepts andfeatures of the inventions—such as alternative materials, structures,configurations, methods, circuits, devices and components, software,hardware, control logic, alternatives as to form, fit and function, andso on—may be described herein, such descriptions are not intended to bea complete or exhaustive list of available alternative embodiments,whether presently known or later developed. Those skilled in the art mayreadily adopt one or more of the inventive aspects, concepts or featuresinto additional embodiments and uses within the scope of the presentinventions even if such embodiments are not expressly disclosed herein.

Additionally, even though some features, concepts or aspects of theinventions may be described herein as being a preferred arrangement ormethod, such description is not intended to suggest that such feature isrequired or necessary unless expressly so stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure, however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure, however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Parametersidentified as “approximate” or “about” a specified value are intended toinclude both the specified value and values within 10% of the specifiedvalue, unless expressly stated otherwise. Further, it is to beunderstood that the drawings accompanying the present application may,but need not, be to scale, and therefore may be understood as teachingvarious ratios and proportions evident in the drawings. Moreover, whilevarious aspects, features and concepts may be expressly identifiedherein as being inventive or forming part of an invention, suchidentification is not intended to be exclusive, but rather there may beinventive aspects, concepts and features that are fully described hereinwithout being expressly identified as such or as part of a specificinvention, the inventions instead being set forth in the appendedclaims. Descriptions of exemplary methods or processes are not limitedto inclusion of all steps as being required in all cases, nor is theorder that the steps are presented to be construed as required ornecessary unless expressly so stated.

I claim:
 1. A measurement system comprising: a gain chain configured toamplify an analog input signal; a range selector configured to select again between the analog input signal and a plurality ofanalog-to-digital converter (ADC) outputs from a plurality of ADCs,wherein each ADC output has a path, and a gain of each output path ismade up of a plurality of gain stages in the gain chain; and a mixerconfigured to combine the plurality of ADC outputs into a single mixedoutput, and wherein: the plurality of ADCs comprises a first ADC and asecond ADC; and the combining the plurality of ADC outputs is performedin accordance to: mixed output=αE_(first)+(1−α)E_(second) where:E_(first) is the output of the first ADC; E_(second) is the output ofthe second ADC; and α is a mixing parameter that varies from one tozero.
 2. The system of claim 1 comprising three or more ADCs.
 3. Thesystem of claim 1, wherein at least one of: a first portion of the gainchain is connected to a first one of the plurality of ADCs and a secondportion of the gain chain is connected to a second one of the pluralityof ADCs; and the plurality of ADCs comprises at least two types of ADCs.4. The system of claim 3, wherein the range selector selects a gain forthe first one of the plurality of ADCs from the first portion of thegain chain and selects a gain for the second one of the plurality ofADCs from the second portion of the gain chain.
 5. The system of claim1, wherein each of the gain stages in the gain chain is connected toeach of the plurality of ADCs via one or more switch banks.
 6. Thesystem of claim 5, wherein the range selector selects a first portion ofthe shared gain stages for a first one of the plurality of ADCs and asecond portion of the shared gain stages for a second one of theplurality of ADCs by setting switches in the one or more switch banks.7. The system of claim 5, wherein the range selector comprises a firstand second multiplexer and, wherein the first multiplexer selects thefirst portion of the shared gain stages; and the second multiplexerselects the second portion of the shared gain stages.
 8. The system ofclaim 7, wherein selection of the first portion of the shared gainstages comprises configuring a gain for the first one of the pluralityof ADCs and selection of the second portion of the shared gain stagescomprises configuring a gain for the second one of the plurality ofADCs.
 9. The system of claim 8, wherein the configuring a gain for thefirst and second one of the plurality of ADCs comprises configuring thegains according to at least one range of the input signal.
 10. Thesystem of claim 1, wherein: the gain of each output path issubstantially the same; and the mixer averages the outputs from eachpath to reduce noise in the single output.
 11. A measurement systemcomprising: a gain chain configured to amplify an analog input signal; arange selector configured to select a gain between the analog inputsignal and a plurality of analog-to-digital converter (ADC) outputs froma plurality of ADCs, wherein each ADC output has a path, and a gain ofeach output path is made up of a plurality of gain stages in the gainchain; and a mixer configured to: when the input signal is in a firstrange, select an output from a first ADC as a single mixed output; whenthe input signal is in a second range, select an output from a secondADC as the single mixed output; and when the input signal is in betweenthe first and second ranges, select a mix of the outputs from the firstand second ADCs as the single mixed output.
 12. The system of claim 11,wherein the system: maintains the second ADC online during a firsttransition period when the input signal is in the first range; andmaintains the first ADC online during a second period when the inputsignal is in the second range.
 13. The system of claim 12, wherein therange selector is configured to configure a gain for at least one of thefirst ADC and second ADC based on an anticipated range of the inputsignal.
 14. The system of claim 12, wherein, during a hysteresis period,the system: maintains the first ADC offline; maintains the second ADConline; and maintains a gain of the second ADC constant.
 15. The systemof claim 14, wherein the hysteresis period is between the firsttransition period and the second transition period.
 16. A measurementsystem comprising: a gain chain configured to amplify an analog inputsignal; a range selector configured to select a gain between the analoginput signal and a plurality of analog-to-digital converter (ADC)outputs from a plurality of ADCs, wherein each ADC output has a path,and a gain of each output path is made up of a plurality of gain stagesin the gain chain; and a mixer configured to combine the plurality ofADC outputs into a single mixed output, wherein the plurality of ADCoutput paths comprises: two ADC output paths that can independently beconfigured into a high range and a low range path; the low range pathhaving a first gain for converting the analog input signal; the highrange path having a second gain for converting the analog input signal,the second gain being lower than the first gain; a mixing deviceconfigured to combine an output of the lower range with an output of thehigher range; and a device configured to vary an amount of gain combinedfrom the low range path and the high range path.
 17. The system of claim16, wherein the high range path is connected to a first gain chain andthe low range path is connected to a second gain chain.
 18. The systemof claim 16, further comprising a selector to select gain stages of thefirst gain chain for the first gain and to select gain stages of thesecond gain chain for the second gain.
 19. The system of claim 16,wherein each of the first and second gains comprises gain stages in again chain common to the low range path and the high range path.
 20. Amethod comprising: amplifying an analog input signal using a gain chain;selecting a gain between the analog input signal and a plurality ofanalog-to-digital converter (ADC) outputs from a plurality of ADCs,wherein each ADC output has a path, and a gain of each output path ismade up of gain stages in the gain chain; and combining the plurality ofADC outputs into a single mixed output, wherein each of the gain stagesin the gain chain is connected to each of the plurality of ADCs via oneor more switch banks.
 21. The method of claim 20, wherein a firstportion of the gain chain is connected to a first one of the pluralityof ADCs and a second portion of the gain chain is connected to a secondone of the plurality of ADCs.
 22. The method of claim 20 furthercomprising: configuring two ADC output paths independently into a highrange and a low range path; applying a first gain from the low rangepath to convert the analog input signal; applying a second gain from thehigh range path to convert the analog input signal, the second gainbeing lower than the first gain; combining an output of the lower rangewith an output of the higher range; and varying an amount of gaincombined from the high range path and the low range path.